Vacuum pouring apparatus



1956 R. 1... SOUTHERN VACUUM POURING APPARATUS Filed NOV. 22, 1954 INVENTOR Raymond L.Southern.

Vacuum Pump Induction Heofi ng Generator Flow-Control 0 m m 8 d5 n n m E d "M u T United States Patent O VACUUM POURING APPARATUS Raymond L. Southern, New Kensington, Pa., assignor to Allegheny Ludlum Steel Corporation, Brackenridge, Pa., a corporation of Pennsylvania Application November 22, 1954, Serial No. 470,478

5 Claims. (Cl. 22-73) This invention relates to vacuum apparatus and in particular to apparatus for effectiving the vacuum pouring of molten metal.

Recently, there has been considerable interest in the vacuum melting and vacuum casting of molten metal to effect the degassing of such molten metal and obtain a more uniform and clean composition. The known vacuum melting and vacuum casting apparatus are quite complicated in design and expensive in construction while being limited with respect to the size of ingots which can be cast.

An object of this invention is to provide a vacuum apparatus for pouring molten metal therethrough and in which the molten metal elfects the seals to maintain the vacuum during the pouring of the metal.

Another object of this invention is to provide apparatus for vacuum treating molten metal to degas the metal as the molten metal flows from a ladle to a mold, the ladle and the mold being exposed to atmospheric conditions. A Other objects of this invention will become apparent from the following description when taken in conjunction with the accompanying drawing, the single figure of which is a view in elevation and partly in section of a vacuum pouring apparatus embodying the teachings of this invention.

Referring to the drawing, the invention is illustrated with reference to vacuum pouring apparatus shown generally at for treating molten metal 12 as it flows from a ladle 14 to a mold 16. The vacuum pouring apparatus shown generally at 10 comprises a plurality of parts such as a tundish 18, an elongated holding unit 20, a vacuum chamber 22 and a valve structure 24 on which the ladle 14 is mounted.

The tundish 18 is formed of a suitable refractory material26 disposed within metallic walls and base 28, the tundish having a teeming storage well 30 and a runner 32' provided in the refractory material 26. In order to support the tundish 18 a shaft 34 is connected to the base 28 thereof as by means of supporting flanges 36 and is disposed to be rotated as by means of a suitable indexing mechanism represented by the rectangle 38. The 'indexing'mechanism 38 may be any suitable manually or automatically operated mechanism for effecting a rotation of the shaft 34, to directionally position the runner 32 of the tundish 18 supported thereon to direct the flow of'molten metalfrom the tundish 18 to a predetermined mold 16, only one of which is illustrated in the drawing. In practice a plurality of the molds 16 is preferably disposed in spaced relation about the shaft 34 so that the tundish 18 may be suitably indexed from one to the other of the molds 16 to selectively direct the flow of moltenmetal thereto. 7

The elongated holding unit is formed of outer metallic walls 40 and an inner liner wall 42 of suitable refrac- 'tory material disposed to form a storage well or holding chamber 44 therein. terial'42 of the holding unit 20 is extended downwardly As illustrated the refractory mabelow the base 46 of the holding unit a distance sufiicient to form a nozzle 48 so that when the holding unit 20 is assembled in vertically extending operative relation with respect to the tundish 18, the nozzle 48 will be positioned within the teeming storage well 30 below the upper edge of the runner 32 and the normal level of the molten metal held in the well 30. The nozzle 48 is provided with a restricted orifice 50 to aid in effecting a seal as will be explained more fully hereinafter.

In order to prevent freezing of the molten metal 12 in the chamber 44 and orifice 50 of the nozzle 48, an induction coil 52 is embedded in the refractory material of the liner wall 42 and nozzle 48 preferably throughout the length thereof for efiectively heating the column of molten metal '12 contained in the holding chamber 44. The induction coil 52 is preferably of the hollow coil type having one end thereof connected to a source of water supply (not shown) and the other end connected to a suitable sump or recirculating system (not shown) whereby the coil is suitably cooled to prevent damage thereto during operation. The ends of the coil 52 are provided with suitable terminals 54 and 56 which are connected to a suitable induction heating generator represented by the rectangle 58.

As illustrated the metallic outer wall 40 of the unit 20 terminates at its upper end in a rim flange member 60 which is provided with a groove 62 in its upper surface for receiving a heat resisting gasket 64 therein. The rim 60 is of a size to receive and support the vacuum chamber unit 22 when seated thereon. The vacuum chamber unit 22 may be of any predetermined size and is preferably provided with an outer wall 66 terminating at its lower end ina rim member 68 of a size and configuration to seat on the rim 60 of the unit 20 and the gasket 64 contained therein for effecting a seal between the unit 20 and the chamber 22. The vacuum chamber unit 22 is also provided with a port 70 at its upper end which terminates in a rim member 72 for receiving the valve structure 24. In order to evacuate the chamber 22, a conduit 74 is disposed extending outwardly from the side wall 66 to be connected through a coupling 76 to a suitable vacuum pump represented by the rectangle 78. In order to check the height of the metal 12 in the unit 20, a sighting port 80 is also provided in the vacuum structure 22 being so disposed that the upper end of the holding chamber 44 can be readily viewed. Where desired suitable cooling coils 82 are disposed external of the structure, adjacent to the joints formed between the vacuum structure 22 and the unit 20 and about the conduit 74 adjacent the coupling 76 so as to effectively cool the joints and prevent heat damage to the gaskets in such joints. The coolingcoils 82 are connected to a suitable source (not shown) of cooling fluid, such as water, for effectively cooling the gasketed joints.

The valve structure 24 may be of any suitable type and is preferably of the sliding valve type which can be manually or otherwise operated by actuating the piston 84 to seat the valve (not shown) in the groove 85. In practice, the valve structure 24 is provided with .a lower rim member 86 having a groove 88 therein for receiving a gasket (not shown) of heat'resisting matter, the rim 86 being of a size to seat upon the upper rim 72 of the vacuum structure 22. The valve structure is also provided with an upper rim member 90 having a groove 92 therein for receiving a gasket (not shown) and for effecting a sealed connection with the ladle 14.

In practice, the ladle 14 may be of any suitable size being provided with a downwardly projecting pouring spout 94 and a suitable stopper96 of refractorymaterial therefor. The stopper 96 is carried by a stopper rod '98 which is enclosed in a sleeve 99 of suitablev refractory material for withstanding the eifect of the molten metal 12. The stopper rod 98 is pivotly mounted as at 100 to a lever arm 102 which is disposed for pivotal movement about a fixed pivot 104 when a piston 106 is actuated. The piston 106 may be actuated pneumatically or electromechanically as desired. In the embodiment illustrated, ladle 14 is provided with a downwardly projecting 'wall 108 disposed about the pouring spout 94, the wall 108 terminating in a rim member 110 disposed to seat in sealed relation with the rim 90 of the valve structure 24.

In operation, with the vacuum pouring structure assembled as shown and described and with a ladle 14 seated in sealed relation with the valve structure 24 for supplying molten metal 12 thereto and the tundish 18 positioned to selectively direct the flow of the molten metal 12 to a predetermined mold 16, the valve of the valve structure 24 is operated to its open position and the vacuum pump 7-8 is started and the induction coil 52 is energized. Under such conditions the stopper rod 98 is actuated to raise the stopper 96 to permit the molten metal 12 to flow through the valve structure 24, the vacuum structure 22, the chamber 44 and out of the orifice 50 into the teeming storage well of the tundish 18. The initial flow of the molten metal through the vacuum pouring structure is at a rapid rate until the teeming storage well 30 is filled. When the well 30 is filled, the restricted orifice immersed therein cooperates to restrict the flow and cause a column of the molten metal 12 to be formed in the chamber 44. In practice, with the pump 78 operating to evacuate the vacuum structure 22 and the chamber 44, it is found necessary to have a column of at least 53 of molten metal 12, when the metal is steel, in the chamber 44 to offset the effect of atmospheric pressure on the surface of the molten metal in the teeming storage well 30 whereby the full effect of the vacuum is obtained to effect degassing of the molten metal as it flows from the ladle 14 through the vacuum structure 22 into the chamber 44 of the unit. Under such conditions the molten metal is degassed and the molten metal will flow from the chamber 44 through the orifice 50 into the teeming storage well 30 and from thence into the runner 32 to the mold 16.

In practice, the flow of molten metal 12 from the ladle 14 is controlled to maintain the height of molten metal in the chamber 44 sufficient to overcome the effect of the atmospheric pressure on the surface of the metal in the well 30, it being noted that the flow of molten metal through the spout 94 of the ladle 14 and through the orifice 50 effectively forms seals for the unit 10 so that the vacuum in the chamber 22 can be maintained for effectively degassing the molten metal as it flows therethrough. While such treatment will not completely degas the molten metal, it does effectively remove oxygen and nitrogen therefrom and to some extent, hydrogen, so that the resulting cast ingot is sufficiently free of the gases normally found in cast material which has not been vacuum treated. In practice, it is found that a vacuum of less than 50 microns is needed in the vacuum chamber 22 to remove a large proportion of the gases from the molten metal.

When it is desired to replace the ladle 14 with another ladle filled with molten metal, the stopper 96 is actuated to close the spout 94 and the valve of the valve structure 24 is thereafter actuated to its closed position. Such operation permits the maintenance of the vacuum in the chamber 22 and on the surface of the column of molten metal 12 in the chamber 44 so that when a replacement ladle 14 is seated in sealed relation on the rim of valve structure 24 and the valve is operated to its open position, the molten metal from the replacement ladle 14 will be immediately subjected to the vacuum as the metal fiows from the ladle.

In practice, a substantially continuous pouring operation may be maintained by replacing the empty ladle 14 with a full ladle and rotating the tundish 18 to selectively direct the flow of molten metal to one of the molds 16 disposed thereabout. After a pour of the molten metal is completed, the column of molten metal in the chamber 44 is drained from the unit 10 simply by releasing the vacuum in the vacuum chamber 22 and by stopping the vacuum pump 78 and opening the valve of the valve structure 24 and lowering the tundish 18 so that the nozzle 48 is above the surface of the metal contained in the teeming storage well 30 therein.

The apparatus of this invention is relatively simple in construction although highly efficient in operation as will be apparent from the foregoing description. The structure can be readily reproduced by anyone skilled in the art. The structure has the further advantage that it can be readily employed in conjunction with steel mill equipment, the only modification of existing equipment required being in providing a ladle which is adapted to seal with the valve structure 24.

I claim:

1. In a vacuum pouring apparatus for degassing molten metal as it is poured from a ladle into a mold, the combination comprising, a tundish having a teeming well and a runner disposed to receive and direct the flow of molten metal into the mold under atmospheric conditions, an elongated pouring chamber disposed between the ladle and the tundish and having an end thereof extending into the teeming well, a storage well in the chamber in communication with the teeming well, means for sealing the other end of the chamber to the ladle for receiving molten metal therefrom, means for evacuating the chamber when metal is poured therethrough into theteeming well, the metal in the teeming well under atmospheric conditions cooperating to maintain a supply of the molten metal in the storage well to effectively seal the chamber whereby molten metal passing through the evacuated chamber is degassed.

2. In a vacuum pouring apparatus for degassing molten metal as it is poured from a ladle into a mold, the combination comprising, a tundish having a teeming well and a runner disposed to receive and direct the flow of molten metal into the mold under atmospheric conditions, an elongated pouring chamber disposed between the ladle and the tundish and having an end thereof extending into the teeming well, a storage wellin the chamber in communication with the teeming well, means for sealing the other end of the chamberto the ladle for receiving molten metal therefrom, means for evacuating the chamber when metal is poured therethrough into the teeming well, the metal in the teeming well under atmospheric conditions cooperating to maintain a supply of the molten metal in the storage well 'to effectively seal the chamber whereby molten metal passing through the evacuated chamber is degassed, and heating means for the storage well disposed to maintain the metal contained therein in a molten condition.

3. In a vacuum pouring apparatus for effectively degassing molten metal as it is poured from a ladle into a mold, the combination comprising, a tundish having a teeming well and a runner disposed to receive and direct the flow of molten metal into the mold under atmospheric conditions, an elongated pouring chamber disposed between the ladle and the tundish and having an end thereof extending into the teeming well, a storage well in the chamber in communication with the teeming well, a passageway disposed at the other end of the chamber for connecting the chamber to the ladle in a sealed communicating relation for receiving molten metal therefrom, means for evacuating the chamber when molten metal is poured therethrough into the teeming well, the metal in the teeming well under atmospheric conditions cooperating to maintain a supply of the molten metal in the storage well to effectively seal the chamber whereby molten metal passing through the evacuated chamber is degassed, and valve means in the passageway between the chamber and ladle disposed to be operated to close the passageway and thereby permit the removal of the ladle while continuing the evacuation of the chamber.

4. In a vacuum pouring apparatus for degassing molten metal as it is poured from a ladle into a mold, the combination comprising, a tundish having a teeming well and a runner disposed to receive and direct the flow of molten metal into the mold under atmospheric conditions, an elongated pouring chamber disposed between the ladle and the tundish and having an end thereof extending into the teeming well, a storage well in the chamber in communication with the teeming well, a passageway disposed at the other end of the chamber for connecting the chamber to the ladle in a sealed communicating relation for receiving molten metal therefrom, means for evacuating the chamber when molten metal is poured therethrough into the teeming well, the metal in the teeming well under atmospheric conditions cooperating to maintain a supply of the molten metal in the storage well to effectively seal the chamber whereby molten metal passing through the evacuated chamber is degassed, valve means in the passageway between the chamber and ladle disposed to be operated to close the passageway and thereby permit the removal of the ladle while continuing the evacuation of the chamber, and means disposed about the storage well for heating the metal contained therein to maintain the metal in a molten condition.

5. In a vacuum pouring apparatus for eflectively degassing molten metal as it is poured from a ladle into spaced molds, the combination comprising, a tundish having a teeming well and a runner disposed to receive and selectively direct the flow of molten metal into a predetermined one of the molds under atmospheric conditions, means for effecting movement of the tundish about a vertiral axis to index the tundish from one mold to another, an elongated pouring chamber disposed between the ladle and the tundish and having an end thereof extending into the teeming well, means for sealing the other end of the chamber to the ladle for receiving molten metal therefrom, a storage well in the chamber in communication with the teeming well, the molten metal in the teeming well cooperating to maintain a supply of the molten metal in the storage well to effectively seal the chamber whereby molten metal passing through the evacuated chamber is degassed.

References Cited in the file of this patent UNITED STATES PATENTS 596,897 May Ian. 4, 1898 1,491,964 Moxham Apr. 29, 1924 2,308,395 Smithson et al Jan. 12, 1943 2,493,594 Reed Jan. 5,. 1950 FOREIGN PATENTS 118,568 Australia June 15, 1944 669,741 Germany Jan. 3, 1939 866,231 Germany Feb. 9, 1953 

1. IN A VACUUM POURING APPARATUS FOR DEGASSING MOLTEN METAL AS IT IS POURED FROM A LADLE INTO A MOLD, THE COMBINATION COMPRISING A TUNDISH HAVING A TEEMING WELL AND A RUNNER DISPOSED TO RECEIVED AND DIRECT THE FLOW MOLTEN METAL INTO THE MOLD UNDER ATMOSPHERIC CONDITIONS, AN ELONGATED POURING CHAMBER DISPOSED BETWEEN THE LADLE AND THE TUNDISH AND HAVING AN END THEREOF EXTENDING INTO THE TEEMING WELL, A STORAGE WELL IN THE CHAMBER IN COMMUNICATION WITH THE TEEMING WELL, MEANS FOR SEALING TYHE OTHER END OF THE CHAMBER TO THE LADLE FOR RECEIVING MOLTEN METAL THEREFROM, MEANS FOR EVACUATING THE CHAMBER WHEN METAL IS POURED THERETHROUGH INTO THE TEEMING WELL, THE METAL IN THE TEEMING WELL UNDER ATMOSPHERIC CONDITIONS COOPERTING TO MAINTAIN A SUPPLY OF THE MOLTEN METAL IN THE STORAGE WELL TO EFFECTIVELY SEAL THE CHAMBER WHEREBY MOLTEN METAL PASSING THE EVACUATED CHAMBER IS DEGASSED. 